High-selectivity partial oxidation of methane into synthesis gas: the role of the red-ox transformations of rare earth - alkali earth cobaltate-based catalyst components

La1 + xSr1 - xCoO4 (x = 0; 025) and NdCaCoO3.96 compounds with a layered perovskite-like structure synthesized by the solid state method and characterized by XRD, XPS, EDAX and H-2-TPR were used as catalyst precursors for the partial oxidation of methane to synthesis gas. Catalytic tests were carried out in a quartz flow reactor using a CH4/O-2 mixture without dilution with inert gases. The higher activity of the NdCaCoO4 +/- delta-based catalyst in comparison with La1 + xSr1 - xCoO4 is associated with the easier formation of Nd and Ca oxides and metallic cobalt in the course of NdCaCoO4 +/- delta reduction in the POM environment. Preliminary reduction of the catalysts with hydrogen leads to a significant increase in synthesis gas production at 800-850 degrees C. Different activity and selectivity of NdCaCoO4 +/- delta and La1 + xSr1 - xCoO4-based catalysts can also be related to the different morphologies of metal-oxide nanocomposites that appear in the course of the reductive decomposition of cobaltates. (C) 2016 Elsevier B.V. All rights reserved.